body{margin:0; padding:0; border:0; font:12px/1.5 "微软雅黑"; color:#333;}
*{margin:0; padding:0; border:0; list-style:none;}
button{cursor: pointer; background: skyblue;}
.chuangkou{width: 300px; height: 200px; background: pink; display: none; position: fixed; left: 50%; top: 50%; margin-left: -150px; margin-top: -100px;}